1. Field of the Invention
The present invention relates to optical device systems that use tripod heads.
2. Description of Related Art
A tripod-supported camera is one example of an optical device system using a tripod head. When a camera is mounted to the tripod with a tripod screw, anchoring the camera and changing the posture of the camera are effected using a manual posture locking mechanism and a posture varying mechanism provided in the tripod, respectively.
With conventional optical device systems, when the scene or object that is to be photographed by the camera (i.e., the camera setup) is to be changed, it is necessary to let go of the camera to release the tripod posture locking mechanism. Hence, changing the camera setup is not as easy as it is for hand-held models. In particular, for example, in an automatic focus camera, the automatic focus adjustment is performed in accordance with the operational state of the camera operation member, e.g., the shutter release button. Therefore, if the photographer has to release the camera to perform a setup change, then it is impossible to continue the automatic focus adjustment state in accordance with the operational state of the operation member prior to the setup change.
For example, a one-shot focus function is known wherein, after focusing has been achieved by depressing the camera release button half way, the focus adjustment state achieved thereby is preserved, i.e., the focus is locked. When the shutter release button is released in order to change the camera setup and the release button is again depressed half way to take a photograph after changing the setup, the automatic focus adjustment operation must be performed again because the focus state prior to changing the camera setup is not preserved. In addition, keeping the shutter release button half-depressed and locking or releasing the tripod posture with the other hand, in order to change the camera setup while keeping the camera focused, is virtually impossible with telephoto lenses and the like.